The present invention relates to an apparatus and a method for measuring zonal inking on printed products.
A printing material is moved successively through a plurality of printing units of a press during a printing operation and a printing ink is applied to the printing material in each printing unit. A separate printing unit and corresponding inking unit is provided for each printing ink. The inking unit of each printing unit has an ink metering device, the ink metering device comprising a number of inking zone setting elements, which are also designated ink slides or ink blades, corresponding to the number of inking zones to be printed on the printing material. A quantity of printing ink passes to an ink fountain roll or a ductor roll of the inking unit in each inking zone as a function of the respective inking zone setting element. The quantity of ink passed onto the ductor roll is transferred by a ductor roll or film roll onto an inking unit roll arranged downstream of the doctor roll or film roll and, via further inking unit rolls, is moved in the direction of a forme cylinder or plate cylinder of the respective printing unit. A transfer cylinder or rubber-covered cylinder interacts with the forme cylinder to transfer the printing ink from the forme cylinder to the printing material.
From the prior art, it is already known to measure the zonal inking established on the printing material during printing and, depending on this measurement, to control the zonal inking of the inking units involved in the printing. For this purpose, measurement regions are generally printed outside a subject on the printing material are measured. However, it is also possible for measurement regions within the subject to be measured. The measurement regions are also referred to as print control elements.
Measuring devices which are based on a densitometric and/or calorimetric and/or spectral measuring principle are used to measure the zonal inking. According to the prior art, in this case each inking zone of a printed product to be measured is either assigned an individual, stationary measuring device or there is a common measuring device for a plurality or all of the inking zones, which is moved in a traversing manner along the printed product to be measured. Stationary or static apparatuses for measuring the zonal inking, which have a separate measuring device for each inking zone, permit fast measurement of a printed product but are expensive because of the high expenditure on hardware. Traversing apparatuses for measuring the zonal inking, which have only one measuring device moved along the inking zones, are less expensive but need a longer time to measure a printed product.